In my opinion, if water is not draining out of the crop into the digestive tract, there is usually a blockage somewhere.
If she aspirated you would know about it because she would be coughing and spluttering. I had a pullet aspirate whilst I was doing crop surgery. Her breathing was raspy and wheezy for a few days but she recovered without antibiotics, so whilst it is to be avoided, it is not necessarily a death sentence.
I would examine her thoroughly to see if there is any abdominal swelling, either between the legs or below the vent. What does her poop look like? How does her body condition feel? Is her breast bone sharp under the skin or reasonably well padded. Compare her by feeling other healthy chickens.
If you genuinely feel that she has an impacted crop and she is feeling skinny, then you have to weigh up the risks of aspiration associated with vomiting against the risk of dying from an impaction. If she is skinny, then it suggests that it has been going on for some time and you need to take action before she gets too weak to recover. Vomiting will allow you to empty some of the contents of the crop which then gives you space to massage the contents that are left.... usually the troublesome bit. Vomiting can also help to break up any sediment/debris that has settled in the bottom of the crop and may be blocking the outlet by massaging in that inverted position.
If you decide to vomit her, tip her slightly to the right when you lower her head below her body so that the oesophagus is slightly lower than the trachea which will reduce the chance of her aspirating.
Once you have some space in the crop, I would massage 4 or more times a day and only give her liquid food... pellets soaked in plenty of warm water with a bit of vegetable oil. No access to anything fibrous... grass/hay/straw/bedding.... and no solid food. If she is skinny, she will benefit from a heat source, ideally a heating pad as she will not have enough nutrition or condition to maintain her body temperature.
